Advanced gate technology for sub-0.25 micron CMOSFETs

As CMOS technology is scaled into the sub-0.25 μm regime, the poly-Si gate depletion effect becomes more problematic. This paper discusses various technological approaches to eliminating this effect. It is shown that poly-SiGe is an especially promising alternative gate material because it can be integrated into an existing CMOS process with relative ease. As compared to poly-Si gate technology, poly-Si 0.8 Ge 0.2 gate technology provides improved resistance to the gate-depletion effect, improved tradeoff between the gate-depletion effect and the boron penetration problem for p-channel devices, and superior device reliability. The viability of poly-Si 0.8 Ge 0.2 as a gate material for sub-0.25 μm CMOS technology is demonstrated in the fabrication of 0.1 μm channel-length MOSFETs.